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United States Patent | 5,699,418 |
Jones | December 16, 1997 |
A single phase locked loop based device is used to detect alert tones and to decode data in caller display services signalling systems. The device has two sets of components (resistors) to configure the device to perform tone detection and data decoding. One or both of the sets of components are connected to the device by an electronically controlled switch.
Inventors: | Jones; David Richard (Pencisely, GB) |
Assignee: | Northern Telecom Limited (Montreal, CA) |
Appl. No.: | 620414 |
Filed: | March 22, 1996 |
Mar 24, 1995[GB] | 9506027 |
Current U.S. Class: | 379/142.04; 375/222; 375/327; 375/376; 379/372 |
Intern'l Class: | H04M 001/56; H04M 015/06; H04B 013/02; H03D 003/18 |
Field of Search: | 379/93,95,96,97,98,127,142,157,201,215,372,373,376,377 375/222,327,376 370/261,522,526 |
4369338 | Jan., 1983 | Soulliard | 179/84. |
4677663 | Jun., 1987 | Szlam | 379/211. |
4860340 | Aug., 1989 | Suzuki | 379/74. |
5263084 | Nov., 1993 | Chaput et al. | 379/215. |
5537448 | Jul., 1996 | Schwarz et al. | 375/376. |
5574777 | Nov., 1996 | Lewis | 379/142. |
Foreign Patent Documents | |||
36 30 471 | Apr., 1988 | DE. |